Method of operating a virtual private network

ABSTRACT

A method of operating a virtual private network includes the steps of: (a) dialing a custom number; (b) receiving the custom number at a switch ( 20 ) of a first carrier; (c) routing the call to a switch ( 18 ) of a second carrier based on having received the custom number; and (d) when the call to the switch ( 18 ) of the second carrier includes a plain old telephone number translation of the customer number, routing the call over the second carrier to a service switching point ( 26 ) of a third carrier.

FIELD OF THE INVENTION

The present invention relates generally to the field oftelecommunications and more particularly to a method of operating avirtual private network.

BACKGROUND OF THE INVENTION

Companies often use abbreviated dialing plans at a location. This allowsthe user to dial an internal number (abbreviated number) to reach otherpeople within the same location. Virtual private networks (VPN) haveallowed companies having several locations in the same Local Access andTransport Area (LATA) to share the abbreviated dialing plan. The VPNallows the various locations of a company to also provide other featuressuch as call transfer, multiway calling, and call forwarding. A companythat decides to use a VPN can provide all these features without buyingexpensive Private Branch Exchanges (PBX) for each location and withouthaving to lease lines between each of the locations. This has providedthe customer with flexibility and cost savings over setting up astandard private network. Unfortunately, companies that have locationsin two or more LATAs could not use a VPN to provide these services. Thisis because the present regulatory environment requires two or morecarriers when connecting two separate LATAs using the Public SwitchedTelephone Network (PSTN). As a result, these customers were required tolease lines between the LATAs and use access codes for the variouslocations, to obtain services similar to a VPN.

Thus there exists a need for a method of operating a virtual privatenetwork that works across several LATAs and several service providers.

SUMMARY OF THE INVENTION

A method of operating a virtual private network that overcomes these andother problems includes the steps of: (a) dialing a custom number; (b)receiving the custom number at a switch of a first carrier; (c) routingthe call to a switch of a second carrier based on having received thecustom number; and (d) when the call to the switch of the second carrierincludes a plain old telephone number translation of the customernumber, routing the call over the second carrier to a service switchingpoint of a third carrier.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of an embodiment of a virtual privatenetwork;

FIG. 2 is a schematic diagram of an embodiment of a virtual privatenetwork;

FIG. 3 is a flow chart of an embodiment of the steps used in operating avirtual private network; and

FIG. 4 is a flow chart of an embodiment of the steps used in operating avirtual private network.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic diagram of an embodiment of a virtual privatenetwork 10. In this embodiment, the provider of the virtual privatenetwork 10 is not the local provider in LATA-1, LATA-2 or LATA-3. When acustomer dials an on-network telephone number from a telephone 12 inLATA-1 of an originating carrier, a service switching point (SSP-A) 14receives the dialed number. A service switching point is an intelligentnetwork switch. The on-network number can be 4-11 digit number and thecustomer does not have to dial an access code before dialing theon-network number. The SSP-A 14 performs a number identifier operationto determine if the call should be routed over a private line 16 to anintermediate carrier switch 18. The number identification operation isperformed in one embodiment by comparing the received number with apredefined set of numbers. In one embodiment, the predefined set ofnumbers includes all the on-network telephone numbers for a particularvirtual private network. When the number belongs to the predefined setof numbers, then the call is routed to the intermediate carrier switch18. In one embodiment the intermediate carrier switch 18 is aninterexchange carrier (IXC) point of presence (POP) switch. Theintermediate carrier switch 18 is connected to other SSPs, such as SSP-B20.

The intermediate carrier switch 18 is connected by an intelligentnetwork 22 to a network carrier Service Control Point (SCP) 24. A SCPprovides a number of intelligent functions, including routing andbilling information for calls to a SSP. When the intermediate carrierswitch 18 receives the call over the private line 16, it encounters acustom dialing plan trigger. The intermediate carrier switch 18 thensends a query over the intelligent network 22 to the SCP 24. The query(information analyzed query) will include at least the calling partydirectory number (calling party telephone number) and the dialed digits(on-network telephone number). The SCP 24 will analyze the query andreturn a message including routing instructions. The message willinclude at least the plain old telephone number translation (directorynumber) of the on-network number. In another embodiment the message willinclude a signaling indication and may also include primary trunk group,secondary trunk group, primary carrier and alternate carrier. Theprimary trunk group defines a particular line (private line) over whichthe call should be routed if possible. The primary carrier defines apreferred interexchange carrier over which the call should be routed ifpossible.

Upon receiving the message and routing instructions the intermediateswitch 18 routes the call based on the routing instructions. If thecustomer at telephone 12 dialed an on-network number of a facilityconnected to SSP-E 26 (terminating service switching point) in LATA-3,the call would be routed through the intermediate carrier's network 28to an intermediate switch 30. When the message includes the signalingindication, the call is routed by the intermediate switch to the SSP-E26 over a private line 32. The SSP-E 26 then routes the call to thecalled customer.

When the message does not include the signaling indication, theintermediate switch 30 triggers on the plain old telephone number. Theintermediate switch 30 sends a query (routing query) to a second servicecontrol point (SCP) 34. The routing query includes the plain oldtelephone number and the calling telephone number. The SCP 34 thendetermines if the plain old telephone number and the calling telephonenumber belong to the same virtual private network. When the plain oldtelephone number and the calling telephone number belong to the samevirtual private network, then the call is routed over a private line 32.When the plain old telephone number and the calling telephone number donot belong to the same virtual private network, the call is routed overpublic facilities to SSP-E.

If the customer at telephone 12 dialed an on-network number of afacility connected to SSP-C 36 or SSP-D 38 in LATA-2, the intermediateswitch 18 would route the call through the intermediate carrier'snetwork 28 to an intermediate switch 40. In one embodiment theintermediate carrier's network is a private line connecting the switches18, 40. The intermediate switch 40 in one embodiment then routes thecall over public facilities to SSP-C 36 or SSP-D 38. In anotherembodiment, the signaling indication tells the switch 40 to route thecall over private facilities 42, 44 to SSP-C 36 or SSP-D 38. Asexplained above the intermediate switch 40, in one embodiment, triggerson the call and sends a query to the SCP 24 to determine if the plainold telephone number and the calling number are part of the same virtualprivate network. When the numbers are part of the same virtual privatenetwork, the intermediate switch 40 routes the call over private lines42, 44. Using the method described above, a virtual private networkconnecting facilities connected to SSP-A 14, SSP-B 20, SSP-C 36, SSP-D38, SSP-E 26 has been described. The virtual private network worksacross multiple LATAs and multiple service providers.

FIG. 2 shows a schematic diagram of another embodiment of a virtualprivate network 50. In this case the call originates from LATA-1 havinglocal exchange carrier (LEC-1). In this embodiment, the network carrierproviding the virtual private network service is the same as LEC-1. Auser dials a number (on-network number) on telephone 52 to initiate acall. SSP-A 54 of the first carrier (LEC-1) receives the number. TheSSP-A 54 triggers on the number and sends a query to the network servicecontrol point (SCP) 55 over an intelligent network 56. The queryincludes the number dialed. The SCP 55 responds with a plain oldtelephone number translation of the number and a signaling indication inone embodiment. The SSP-A 54 then routes the call over a private line 58to a switch 60 of an intermediate carrier (second carrier), when thecall is directed to facilities connected to either SSP-E 62 in LATA-2 orSSP-F 64 in LATA-3. When the call is directed to facilities in LATA-1(first local access and transport area), such as SSP-B 66 or SSP-C 68,SSP-A 54 in one embodiment contains sufficient information to route thecall over private facilities 70, 73 to SSP-B 68 or SSP-C 68. Note thatSSP-B and SSP-C 68 are connected by private facilities 74. In anotherembodiment, SSP-A 54 sends a query to SCP 55 and then routes the callover public or private facilities to SSP-B 66 or SSP-C 68.

The switch 60 routes the call based on the plain old telephone number(POTS) through the second carrier to a switch 76, when the call is tofacilities connected to SSP-E 62. When the SCP 55 included a signalingindication in its routing message, then the switch 76 routes the callover private facilities 78 to SSP-E 62. When the SCP 55 did not includethe signaling indication in its routing message, the switch 76 routesthe call over public facilities to SSP-E 62 based on the POTStranslation of the dialed number.

When the call is directed to a facility connected to SSP-F 64, theswitch 60 routes the call through the second carrier's network to aswitch 80. In one embodiment, the switch 60 is connected to switch 80 bya private line 82. In one embodiment, the switch 80 routes the call overpublic facilities to SSP-F 64, based upon the POTS number. In anotherembodiment the switch 80 routes the call over private facilities 84 toSSP-F, based upon the signaling indication. In yet another embodiment,the switch 80 routes the call over private facilities 84 after sending aquery to SCP 55. The SCP 55 determines that the calling party and calledparty are part of the same virtual private network.

FIG. 3 is a flow chart of an embodiment of the steps in used inoperating a virtual private network. The process starts, step 100, by auser dialing a number at step 102. The number is received at an switchat step 104. At step 106 it is determined if the dialed number belongsto predefined set of numbers. When the number does not belong to thepredefined set of numbers (predetermined group of numbers), then otherprocessing is performed at step 108. When the number does belong to thepredefined set of numbers (predetermined set), the call is routed over aprivate line at step 110. At step 112, a custom dialing plan (CDP)trigger is performed at an intermediate carrier switch. The intermediatecarrier switch sends a query to a network SCP at step 114. At step 116,the switch receives a message (response) including routing instructions.The call is routed using the routing instructions at step 118, whichends the process at step 120.

FIG. 4 is a flow chart of another embodiment of the steps in used inoperating a virtual private network. The process starts, step 130, whena customer number is dialed at step 132. A custom number is a numberthat does not conform to a standard number or dialing plan (e.g., theNorth American Numbering Plan). The customer number is received at afirst carrier's switch at step 134. The SSP routes the call to a switchat a second carrier at step 136. The switch determines if the callincludes a plain old telephone number translation of the custom numberat step 138. When the call does include the a plain old telephone (POTS)number translation of the custom number, the call is routed to a SSP ofa third carrier (terminating carrier) based on the POTS number at step140, which ends the process at step 142.

When the call does not include the POTS number translation of the customnumber, the switch of the second carrier sends a query to a network SCPat step 144. Note that the network SCP can be part of the first carrier,second carrier, third carrier or part of a separate carrier. The switchthen receives routing instructions including the POTS number translationof the custom number at step 146. Based on the POTS number the call isrouted to a second switch of the second carrier at step 148. Next, it isdetermined if the call includes a signaling indicator (receivedsignaling indicator) at step 150. When the signaling indicator isincluded, the call is routed over a private line at step 152. The callis connected to the SSP of the third carrier at step 140, which ends theprocess at step 142.

When the signaling indicator is not included, a query is sent to asecond SCP to determine if the POTS number and the originating numberare part of the same virtual private network at step 154. When the POTSnumber and the originating number are part of the same virtual privatenetwork, the call is routed over a private line at step 152. The call isconnected to the SSP of the third carrier at step 140, which ends theprocess at step 142. When the POTS number and the originating number arenot part of the same virtual private network, the call is routed overthe public network at step 156. The call is received at the SSP in thethird carrier at step 140, which ends the process at step 142.

Thus there has been described a method of operating a virtual privatenetwork works across several LATAs and several service providers. Whilethe invention has been described in conjunction with specificembodiments thereof, it is evident that many alterations, modifications,and variations will be apparent to those skilled in the art in light ofthe foregoing description. Accordingly, it is intended to embrace allsuch alterations, modifications, and variations in the appended claims.

What is claimed is:
 1. A method of operating a virtual private network,comprising the steps of: (a) receiving a number at a service switchingpoint of a first carrier; (b) sending a query to a service controlpoint; (c) receiving a response containing a routing instructionsincluding a plain old telephone number translation of the number; (d)routing a call over a private line to a switch of an intermediatecarrier; (e) routing the call based on the routing instructions.
 2. Themethod of claim 1, wherein step (e) further includes the steps of: (e1)routing the call over the private line from the intermediate carrier toa service switching point of a terminating carrier.
 3. The method ofclaim 1, wherein step (a) consists of receiving four dialed digits.
 4. Amethod of operating a virtual private network, comprising the step of:(a) receiving a number at a service switching point of a first carrier;(b) sending a query to a service control point; (c) receiving a billinginformation (d) routing a call over a private line to a switch of anintermediate carrier; and (e) routing the call over the private linefrom the intermediate carrier to a service switching point of aterminating carrier.
 5. The method of claim 4, wherein step (b) furtherincludes the step of: (b1) receiving a response containing a routinginstructions.
 6. The method of claim 5, wherein step (b) furtherincludes the step of: (b2) receiving a response containing a plain oldtelephone number translation of the number.
 7. The method of claim 5,wherein step (b1) consists of receiving a signaling indicator as part ofthe routing instructions.
 8. The method of claim 7, wherein step (e)further includes the steps of: (e1) determining if the routinginstructions include the signaling indicator; and (e2) when the routinginstructions include the signaling indicator, routing the call over theprivate line.